Sweet Potato Purée

In a shallow baking pan lined with foil bake the sweet potatoes, pricked in several places, in the middle of a preheated 350 °F. oven for 1 1/2 hours, or until they are very tender, let them cool until they can be handled, and peel them. Force the sweet potatoes through the medium disk of a food mill into a heavy saucepan and add the orange juice, the butter, and the sugar. The sweet potato purée may be prepared up to this point 1 day in advance and kept covered and chilled. Heat the sweet potato purée over moderately low heat, stirring, until it is heated through and the butter is melted and season it with salt and pepper.